Police this morning confirmed Aaron Marks, 38, of Iluka, had passed away in hospital on Wednesday.

His death comes after a mystery incident - about 2am on Sunday morning, Mr Marks was found unconscious on the footpath in River St with serious head injuries.

He was treated at the scene by NSW Ambulance paramedics, before being airlifted to the Gold Coast University Hospital.

Aaron Marks, 38, died in hospital after a brutal attack in Ballina on Sunday morning.NSW Police

Mr Marks was pronounced dead at 1.30pm on Wednesday, May 16, after doctors at Gold Coast University Hospital diagnosed him as brain dead.

Richmond Police District Inspector Tom Kirk said police still had no leads surrounding the incident.

Enquiries are ongoing as the Richmond Police District's Strike Force Bulgundara continues to investigate the circumstances surrounding the incident.

They are now being assisted by officers from State Crime Command's Homicide Squad.

Police have information Mr Marks left licensed premises on River Street at Ballina, about 11.55pm on Saturday 12 May 2018.

Detectives are urging anyone with information or anyone who was in the area at the time to come forward.

Richmond Police District has established Strike Force Bulgundara to investigate after a man found with serious head injuries in Ballina, remains in a critical condition in hospital.NSW Police

Anyone with information in relation to this incident to call Ballina Detectives on 6681 8699 or Crime Stoppers on 1800 333 000 or use the Crime Stoppers online reporting page: https://nsw.crimestoppers.com.au/ Information you provide will be treated in the strictest of confidence.